The present invention relates in general to balloon catheters employed in the treatment of vascular diseases. More particularly, the present invention relates to a bifurcated catheter assembly which has two dilation balloons in parallel at the distal end of a single catheter shaft. The bifurcated catheter assembly provides an improved means for treating arterial bifurcations.
In a medical procedure known as percutaneous transluminal coronary angioplasty (PTCA), a balloon catheter is used to treat a coronary artery (or other vessel) which has become narrowed or restricted due to the accumulation of plaque along the artery wall. In the PTCA procedure, a balloon catheter is inserted percutaneously and is advanced through the lumen of the coronary artery to the site of a stenosis. The balloon is then inflated to press the plaque against the artery wall thereby dilating the lumen of the artery and establishing adequate blood flow.
After the PTCA procedure has been performed, a stent (which is well known in the art) may be deployed in the treated area to prevent restenosis and maintain a clear pathway for the flow of blood. A balloon catheter with an expandable stent mounted over the balloon is advanced through the lumen until the stent is in the desired location. The balloon is then temporarily inflated thereby expanding and implanting the stent in the vessel. The balloon is then deflated and the balloon catheter assembly is removed from the lumen, leaving the implanted stent in the vessel to support the vessel wall and prevent development of restenosis.
Although most diseased arteries can be successfully treated in this manner using conventional balloon catheters and stents, arteries which are diseased at a bifurcation are difficult to treat with the devices currently available. For example, when a conventional balloon catheter is used to treat one of the vessel passages at a bifurcation during PTCA, the pressure from the expansion of the balloon in the treated passage can restrict the flow of blood to the untreated passage by pushing the carina over the ostium of the untreated vessel. In addition, the pressure of the balloon in the treated passage may shift the plaque from the treated passage to the untreated passage. If sufficient plaque is shifted to the untreated passage, the ostium of the untreated passage can becomes so occluded that it becomes difficult or impossible to insert a guide wire and catheter to perform a PTCA in the untreated vessel.
Deploying a stent at a bifurcation is also very challenging because the stent must overlay the entire diseased area of the bifurcation, yet not itself compromise blood flow. Conventional stents are designed to repair areas of blood vessels that are removed from bifurcations and, since a conventional stent generally terminates at right angles to its longitudinal axis, the use of conventional stents in the region of a vessel bifurcation may result in blocking blood flow of a side branch (commonly referred to as xe2x80x9cjailingxe2x80x9d the side branch) or fail to repair the bifurcation to the fullest extent necessary. To be effective, the stent must overlay the entire circumference of the ostium to a diseased portion and extend to a point within and beyond the diseased portion. Where the stent does not overlay the entire circumference of the ostium to the diseased portion, the stent fails to completely repair the bifurcated vessel.
To overcome the problems and limitations associated with the use of conventional stents, a Y-shaped stent has been proposed for the treatment of bifurcations. Such a stent has the advantage of completely repairing the vessel at the bifurcation without obstructing blood flow in other portions of the bifurcation. In addition, such a stent allows access to all portions of the bifurcated vessel should further interventional treatment be necessary. In a situation involving disease in the origin of an angulated aorta-ostial vessel, such a stent would have the advantage of completely repairing the vessel origin without protruding into the aorta or complicating repeat access. The proposed Y-shaped stent provides an improved device for repairing bifurcations, however, the delivery and deployment of such a stent cannot be easily accomplished with a conventional balloon catheter.
Because a conventional balloon catheter is not adequate for treating an arterial bifurcation, many physicians currently employ a xe2x80x9ckissing balloonsxe2x80x9d technique in which two separate balloon catheters are inserted into a guide catheter and each balloon tracks over a separate guide wire. The guide catheter is advanced to a point proximal of the bifurcation site and two guide wires are then advanced from the distal end of the guide catheter into separate vessel passages. The two balloon catheters then track the guide wires into the respective passages. The balloons are simultaneously inflated using either separate inflation media or from a single source using a manifold which divides the flow. The two catheters are used together for PTCA or stenting so that both vessel passages at a bifurcation site can be treated simultaneously.
Although generally effective, the use of two single balloon catheters to treat arterial bifurcations has significant drawbacks. For example, the presence of two similar catheters exiting the proximal end of the guide catheter makes it difficult for a physician to manage both devices without becoming confused as to which catheter controls which balloon. Furthermore, the presence of two balloon catheters within one guide catheter creates a large device profile thereby limiting the amount of radiopaque dye which can be injected into the vessel to allow the physician to view the bifurcation.
Efforts have been made to develop a balloon catheter which is designed specifically for the treatment of arterial bifurcations. Such efforts have led to the proposal of a Y-shaped balloon disposed at the distal end of a catheter which is inflated in a bifurcation to treat both passages simultaneously. Although a Y-shaped balloon would provide an improvement over the use of two separate balloon catheters, the proposed device may not be practical due to challenges of manufacturing a Y-shaped balloon, attaching it to a catheter shaft, and properly positioning it at a bifurcated blood vessel. A device of this type is described in the international patent application WO 97/16217 dated Oct. 30, 1995 and entitled Angioplasty Device for Arterial Bifurcation.
Thus, there exists a need for an improved balloon catheter which can be used to effectively treat arterial bifurcations both for PTCA and stent delivery and deployment. It is also desirable that such a balloon catheter be easy to use, inexpensive to manufacture, and constructed from materials which are common in the industry today. The present invention addresses this need.
The present invention provides a bifurcated catheter assembly which can be used to simultaneously dilate stenoses in both the main and the side branch vessels of a bifurcation and also provides a means to quickly and easily deliver and deploy a Y-shaped stent. The invention comprises a single catheter shaft having two individual parallel balloons at the distal end. The parallel balloons track separate guide wires into separate blood vessel passages at a bifurcation and are inflated simultaneously by inflation media from a common source. The present invention is designed primarily for use in coronary arteries, however, it may also be used to treat other vessels such as the renals, abdominal aorta, femoral, and carotid arteries.
The bifurcated catheter assembly of the present invention includes a main catheter body with three lumens in its distal portion. The first lumen is an inflation lumen for pressurized inflation media which is used to inflate and deflate the balloons. The second lumen is a guide wire lumen which contains the tracking guide wire and the third lumen is also a guide wire lumen which contains an integrated guide wire.
Two parallel catheter branches are connected to the distal end of the main catheter body. Each of the parallel catheter branches has two lumens. One lumen is an inflation lumen which communicates with the inflation lumen in the main catheter body and the other lumen is a guide wire lumen in communication with one of the guide wire lumens in the main catheter body. An expandable member such as a balloon is located on the periphery of each catheter branch which is in communication with the inflation lumen in each catheter branch. An inflation notch on the side of each catheter branch allows pressurized inflation media to enter and exit the balloons. The guide wire lumen in each catheter branch extends all the way to the distal end allowing the guide wires to exit distally from the respective branches.
The tracking guide wire is advanced through the main vessel and the integrated guide wire is advanced through the ostium and into the side branch vessel at the bifurcation. With one guide wire advanced into each passage of the bifurcation, the bifurcated catheter assembly is advanced so that the first balloon tracks the tracking guide wire into the main vessel passage and the second balloon tracks the integrated guide wire into the side-branch vessel passage.
The bifurcated catheter assembly can be used at an arterial bifurcation both for PTCA and for stent delivery and implanting. Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features of the invention.